Advanced numerical modelling of mechanical nutted bar anchors for precast concrete connections under tensile loading

This study presents a combined experimental and numerical investigation of a novel anchorage system based on threaded bars with end nut for precast reinforced concrete elements, developed to ensure ductile tensile performance while minimising the required embedment length. The system was evaluated through a comprehensive experimental programme involving monotonic and cyclic tests axial with respect to the bar. This paper presents partial results of monotonic tests with varying embedment length and confinement condition. The results provided insights into failure modes ranging from bond failure to bar rupture and the role of interlocking nuts and stirrup confinement in enhancing tensile capacity. Detailed nonlinear 3D finite element models were developed with the ATENA software with the aim to numerically simulate the tests. The models were set to capture the fundamental non-linear phenomena involved such as concrete cracking, bond-slip interaction, and reinforcement yielding. The adopted modelling strategy provided valuable insights and was set to accurately simulate peak load, crack patterns, and failure mechanisms.